Local Low-dose Anti-PD-L1 Antibodies Improve Antitumor Effects in Oral Squamous Cell Carcinoma.

BACKGROUND/AIM: Immune checkpoint inhibitors are highly effective for treating recurrent and metastatic head and neck cancers. However, they require systemic administration and are associated with immune-related adverse events (irAEs). Reducing therapeutic antibody doses to prevent irAEs is challenging. MATERIALS AND METHODS: Mouse buccal mucosa squamous cell carcinoma cells (Sq-1979) were transplanted into the backs of mice to induce tumors. The antitumor efficacy and tumor immunohistological environment in tumor-bearing mice were compared after administering a standard dose of programmed death-ligand 1 (PD-L1) antibodies systemically (200 mg/body) or 1/10th of the standard dose (20 mg/body) directly to tumors. Mice received four doses of antibody administered in 3-day intervals. Tumor reduction rates and antitumor efficacies were evaluated 21 days after initiating treatment. CD8+T cell counts and PD-L1, PD-1, perforin, and granzyme B levels; CD25 and Foxp3 expression levels; and tumor Tregs were assessed in the resected subcutaneous tumors. RESULTS: The antitumor efficacies in the local low-dose and systemic standard-dose groups were compared with that of the control group. The efficacies of the two treatment groups were similar, and both treatment groups revealed significant antitumor effects compared to the control group. Perforin and granzyme B levels were higher in the local low-dose group (p<0.05). CONCLUSION: Local low-dose administration of anti-PD-L1 antibodies exhibits antitumor efficacy similar to systemic standard-dose administration suggesting that local low-dose administration is useful for treating oral squamous cell carcinoma.

Fibroblast growth factor inhibition by molecular-targeted agents mitigates immunosuppressive tissue microenvironment in hepatocellular carcinoma.

BACKGROUND & AIMS: Combination immunotherapy refers to the use of immune checkpoint inhibitors (ICI) and molecular-targeted agents (MTA), which have recently been approved for the treatment of advanced hepatocellular carcinoma (HCC). Owing to its relatively low antitumor effect (up to 30%), sequential therapy following ICIs treatment is required in patients with HCC. This study aimed to determine the impact of MTAs on the tumor immune microenvironment (TIME). METHODS: We established immune syngeneic orthotopic HCC mouse models using Hep-55.1C and Hep-53.4, and treated them with MTAs (lenvatinib, sorafenib, regorafenib, cabozantinib, and DC101 as anti-vascular endothelial growth factor receptor-2 antibodies, and AZD4547 as a fibroblast growth factor receptor (FGFR)-1/2/3/4 inhibitor) for 2 weeks. Subsequently, alterations in the TIME caused by MTAs were evaluated using immunohistochemistry (antibodies for CD3, CD8, Foxp3, Granzyme B, Arginase-1, NK1.1, F4/80, CD11c, PD-1, and PD-L1). We conducted RNA-seq analysis using lenvatinib- and AZD4547-treated tumors. To confirm the clinical relevance of these findings, we analyzed the transcriptome data of human HCC cells (MHCC-97H) treated with various concentrations of lenvatinib for 24 h using RNA-seq data from the Gene Expression Omnibus database. RESULTS: The number of Foxp3- and F4/80-positive cells in the TIME was decreased in many MTAs. Cabozantinib increased the numbers in NK1.1-, Granzyme B, and CD11c-positive cells. Lenvatinib and AZD4547 increased the number of CD8, Granzyme B, and PD-L1-positive cells. Gene ontology enrichment analysis revealed that lipid metabolism-related genes were downregulated by lenvatinib and AZD4547. In total, 161 genes downregulated by FGFR inhibition in rodent models overlapped with those downregulated by lenvatinib in human HCC cells. CONCLUSIONS: In this study, we showed that cabozantinib activated the innate immune system, and lenvatinib and AZD4547, which commonly inhibit FGFR signaling, altered TIME to a hot immune state by downregulating lipid metabolism-related genes. These findings support the therapeutic use of combination immunotherapies.

The apoptotic effects of NK-92 cells stimulated with an anti-CD226 antibody on MDA-MB-231 triple-negative breast cancer cells.

Research on immunotherapy in breast cancer treatment has recently gained importance. In this context, natural killer (NK) cells have been shown to kill cancer cells without affecting normal cells. Our study used the NK-92 cells that were stimulated with anti-CD226 antibodies (sNK-92) to increase their activity to target MDA-MB-231 triple-negative breast cancer cells. MCF-12A normal breast cells were used as the control in all experiments. The cytotoxic effects of NK-92 and sNK-92 cells on MDA-MB-231 cells were investigated using lactate dehydrogenase tests. The sNK-92 cells were more cytotoxic than NK-92 cells on MDA-MB-231 cells. In contrast, a significant cytotoxic change was not observed in MCF-12A cells cocultured with NK-92 and sNK-92 cells. An increase in granzyme B levels after coculturing with sNK-92 cells was investigated using the granzyme B enzyme-linked immunosorbent assay. The sNK-92 cells secreted more granzyme B than NK-92 cells against MDA-MB-231 cells. This increase was not observed in MCF-12A, indicating that sNK-92 cells specifically target cancer cells. In addition, immunostaining was used to investigate the synthesis level of BAX, CASP3, and CASP9 proteins to determine whether the observed cytotoxic effect was due to apoptosis. These proteins were synthesized more in MDA-MB-231 cells cocultured with sNK-92 than with NK-92 cells. However, no increase in their synthesis was observed in normal breast cells cocultured with NK-92 and sNK-92 cells. In conclusion, NK-92 cells stimulated with anti-CD226 antibodies secrete more granzyme B, resulting in a greater cytotoxic effect by inducing programmed cell death (apoptosis). The fact that the observed effects on breast cancer cells were not observed in normal breast cells indicates that sNK-92 cells specifically target breast cancer cells. These results indicate the potential use of CD226-stimulated NK-92 cells in immunotherapy.

A robust gene prognostic index composed of GZMB, IRF1, and TP63 can stratify the risk of two metastatic urothelial carcinoma cohorts based on immune checkpoint blockade therapy.

BACKGROUND: Immune checkpoint blockade (ICB) therapy has become a first-line treatment option for metastatic urothelial carcinoma (mUC) patients who do not meet the criteria of cisplatin. Still, only a few people can benefit from it, so useful predictive markers are needed. METHODS: Download the ICB-based mUC and chemotherapy-based bladder cancer cohorts, and extract the expression data of pyroptosis-related genes (PRG). The LASSO algorithm was used to construct the PRG prognostic index (PRGPI) in the mUC cohort, and we verified the prognostic ability of PRGPI in two mUC and two bladder cancer cohorts. RESULTS: Most of the PRG in the mUC cohort were immune-activated genes, and a few were immunosuppressive genes. The PRGPI composed of GZMB, IRF1, and TP63 can stratify the risk of mUC. In IMvigor210 and GSE176307 cohorts, the P-values of Kaplan Meier analysis was < 0.01 and 0.002, respectively. PRGPI could also predict ICB response, and the chi-square test of the two cohorts had P-values of 0.002 and 0.046, respectively. In addition, PRGPI can also predict the prognosis of two bladder cancer cohorts without ICB therapy. The PRGPI and the expression of PDCD1/CD274 had a high degree of synergistic correlation. The Low PRGPI group showed prominent characteristics of immune infiltration and was enriched in the immune signal activation pathway. CONCLUSION: The PRGPI we constructed can effectively predict the treatment response and overall survival rate of mUC patients treated with ICB. The PRGPI can help mUC patients achieve individualized and accurate treatment in the future.

Intralesional photodynamic therapy induces apoptosis in basal cell carcinoma and Bowen's disease through caspase 3 and granzyme B.

BACKGROUND: Photodynamic therapy (PDT) is used to treat cutaneous cancers. It may induce cell death through direct and indirect means, including apoptosis, inflammation and certain immune mechanisms, with the depth of penetration as a potential modifying factor. OBJECTIVES: To examine the pathways of apoptosis in the intralesional PDT of basal cell carcinoma (BCC) and intraepidermal squamous cell carcinoma (Bowen's disease). METHODS: Sixteen patients with superficial or nodular BCC and Bowen's disease were treated with intralesional aminolevulinic acid-PDT. Biopsies were taken at baseline and 24 h post-PDT, and sections were examined by immunohistochemistry for the expression of markers of apoptosis, such as caspase 3, involved in the intrinsic apoptotic pathway, granzyme B, a caspase-independent apoptotic mediator, and the proapoptotic markers BAX and BAK. RESULTS: Apoptotic cells stained with TUNEL showed statistically significant staining at 24 h post PDT (p < 0.01 in both BCC and Bowen's lesions). Caspase 3 (p < 0.01 in BCC and p < 0.05 in Bowen's) and granzyme B (p < 0.01 in BCC and p < 0.01 in Bowen's) were significantly increased at 24 h post-PDT. BAX expression was apparently increased compared to baseline in Bowen's lesions at 24 h post-PDT, whereas Bak was upregulated both in BCC and Bowen's disease at baseline and at 24 h post-PDT. CONCLUSION: Intralesional PDT induces apoptosis in BCC and Bowen's disease via common and alternative apoptotic pathways involving granzyme B. Proapoptotic factors Bak in both BCC and Bowen and Bax in Bowen's disease appear to increase by intralesional PDT at 24 h.

Identification of CD8+ T cell subsets that normalize in early-treated people living with HIV receiving antiretroviral therapy.

BACKGROUND: Although combined antiretroviral therapy (cART) has decreased the mortality associated with HIV infection, complete immune reconstitution is not achieved despite viral suppression. Alterations of CD8+ T cells and some of their subpopulations, such as interleukin (IL)-17-producing cells, are evidenced in treated individuals and are associated with systemic inflammation and adverse disease outcomes. We sought to evaluate if different CD8+ T cell subsets are differentially normalized during a clinical follow-up of people living with HIV (PLWH) receiving suppressive cART. METHODS: We explored the changes in the frequencies, activation/exhaustion phenotypes (HLA-DR, CD38, PD-1, and TIM-3), and function (total and HIV-specific cells expressing CD107a, perforin, granzyme B, interferon [IFN]-γ and IL-17) of CD8+ T cells from early-treated PLWH receiving cART in a 1-year follow-up, using a multidimensional flow cytometry approach. RESULTS: Despite continuous cART-induced viral suppression and recovery of CD4+ T cells, after a 1-year follow-up, the CD8+ T cell counts, CD4:CD8 ratio, PD-1 expression, and IL-17 production by CD8+ T cells exhibited incomplete normalization compared with seronegative controls. However, the proportion of CD8+ T cells with an exhausted phenotype (co-expressing PD-1 andTIM-3), and cells co-expressing cytotoxic molecules (Perforin and Granzyme B), reached normalization. CONCLUSIONS: Although suppressive cART achieves normalization of CD4+ T cell counts, only particular subsets of CD8+ T cells are more rapidly normalized in PLWH receiving cART, which could be routinely used as biomarkers for therapy efficiency in these patients.

Trichosanthin cooperates with Granzyme B to restrain tumor formation in tongue squamous cell carcinoma.

BACKGROUND: Tongue squamous cell carcinoma (TSCC) is a common type of oral cancer, with a relatively poor prognosis and low post-treatment survival rate. Various strategies and novel drugs to treat TSCC are emerging and under investigation. Trichosanthin (TCS), extracted from the root tubers of Tian-Hua-Fen, has been found to have multiple biological and pharmacological functions, including inhibiting the growth of cancer cells. Granzyme B (GrzB) is a common toxic protein secreted by natural killer cells and cytotoxic T cells. Our group has reported that TCS combined with GrzB might be a superior approach to inhibit liver tumor progression, but data relating to the use of this combination to treat TSCC remain limited. The aim of this study was to examine the effectiveness of TCS on TSCC processes and underlying mechanisms. METHODS: First, we screened the potential antitumor activity of TCS using two types of SCC cell lines. Subsequently, a subcutaneous squamous cell carcinoma xenograft model in nude mice was established. These model mice were randomly divided into four groups and treated as follows: control group, TCS treatment group, GrzB treatment group, and TCS/GrzB combination treatment group. Various tumorigenesis parameters, such as Ki67, PCNA, caspase-3, Bcl-2 and VEGFA, et al., were performed to determine the effects of these treatments on tumor development. RESULTS: Screening confirmed that the SCC25 line exhibited greater sensitivity than the SCC15 line to TCS in vitro studies. TCS or GrzB treatment significantly inhibited tumor growth compared with the inhibition seen in the control group. The TCS/GrzB combination inhibited tumor growth more than either drug alone. TCS treatment inhibited tumor proliferation by downregulating Ki67 and Bcl2 protein expression while accelerating tumor apoptosis. In the TCS/GrzB-treated group, expression of Ki67 was further downregulated, while the level of activated caspase-3 was increased, compared with their expression in either of the single drug treatment groups. CONCLUSION: These results suggest that the TCS/GrzB combination could represent an effective immunotherapy for TSCC.

Granzyme B PET Imaging Stratifies Immune Checkpoint Inhibitor Response in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a notoriously difficult cancer to treat. The recent development of immune checkpoint inhibitors has revolutionised HCC therapy; however, successful response is only observed in a small percentage of patients. Biomarkers typically used to predict treatment response in other tumour types are ineffective in HCC, which arises in an immune-suppressive environment. However, imaging markers that measure changes in tumour infiltrating immune cells may supply information that can be used to determine which patients are responding to therapy posttreatment. We have evaluated [18F]AlF-mNOTA-GZP, a radiolabeled peptide targeting granzyme B, to stratify response to ICIs in a HEPA 1-tumours, a syngeneic model of HCC. Posttherapy, in vivo tumour retention of [18F]AlF-mNOTA-GZP was correlated to changes in tumour volume and tumour-infiltrating immune cells. [18F]AlF-mNOTA-GZP successfully stratified response to immune checkpoint inhibition in the syngeneic HEPA 1-6 model. FACS indicated significant changes in the immune environment including a decrease in immune suppressive CD4+ T regulatory cells and increases in tumour-associated GZB+ NK+ cells, which correlated well with tumour radiopharmaceutical uptake. While the immune response to ICI therapies differs in HCC compared to many other cancers, [18F]AlF-mNOTA-GZP retention is able to stratify response to ICI therapy associated with tumour infiltrating GZB+ NK+ cells in this complex tumour microenvironment.

Immunotoxins in cancer therapy: Review and update.

Immunotoxins are a novel class of cancer therapeutics that contains a cytotoxic agent fused to a targeting moiety. Various toxic agents from different sources are used in immunotoxin development, including bacterial, plant and human origin cytotoxic elements. Although bacterial and plant-derived toxins are highly toxic and commonly used in immunotoxins, their immunogenicity for human restricted their application in cancer therapy. Here, we discuss the advantages and limitations of bacterial toxins such as Pseudomonas and Diphtheria toxins, plant toxins such as ricin and gelonin, and some endogenous protein of human origin such as RNases and Granzymes. This article will also review different generations of immunotoxins with special focus on immunotoxins which are under clinical trials or approved for clinical use. Finally, current deimmunization strategies for development of new less-immunogenic recombinant immunotoxins will be discussed. ABBREVIATIONS: mAbs: Monoclonal antibodies; EF2: elongation factor 2; ITs: Immunotoxins; DT: Diphtheria toxin; PE: Pseudomonas exotoxin; dgA: de-glycosylated A-chain of ricin; rGel: recombinant de-glycosylated form of gelonin; NKC: natural killer cells; HTR: human transferrin receptor; EGF: epidermal growth factor; GM-CSF: granulocyte-macrophage colony-stimulating factor; DAB389: truncated Diphtheria toxin; B-CCL: B-cell chronic lymphocytic leukemia; RCC: renal cell carcinoma; GVHD: Graft-versus-host disease; EGFR: epidermal growth factor receptor; AML: acute myeloid leukemia; Fab: fragment antigen-binding; dsFv: disulfide-stabilized fragment variable; scFv: single-chain fragment variable; B-ALL: B-lineage Acute Lymphoblastic Leukemia; Fv: fragment variable; HCL: hairy cell leukemia; IL-2R: Interleukin-2 receptor; CR: complete response; CLL: chronic lymphocytic leukemia; ATL: adult T-cell leukemia; DARPins: designed Ankyrin repeat proteins; pmol: picomolar; HAMA: human-anti mouse antibody.

Immunotherapeutic targeting of membrane Hsp70-expressing tumors using recombinant human granzyme B.

BACKGROUND: We have previously reported that human recombinant granzyme B (grB) mediates apoptosis in membrane heat shock protein 70 (Hsp70)-positive tumor cells in a perforin-independent manner. METHODOLOGY/PRINCIPAL FINDINGS: Optical imaging of uptake kinetics revealed co-localization of grB with recycling endosomes (Rab9/11) as early as 5 min after internalization, with late endosomes (Rab7) after 30 min, and the lysosomal compartment (LAMP1/2) after 60 to 120 min. Active caspase-3-mediated apoptosis was induced in mouse CT26 monolayer cells and 3D tumor spheroids, but not in normal mouse endothelial cells. Granzyme B selectively reduced the proportion of membrane Hsp70-positive cells in CT26 tumor spheroids. Consecutive i.v. injections of recombinant human grB into mice bearing membrane Hsp70-positive CT26 tumors resulted in significant tumor suppression, and a detailed inspection of normal mouse organs revealed that the administration of anti-tumoral concentrations of grB elicited no clinicopathological changes. CONCLUSIONS/SIGNIFICANCE: These findings support the future clinical evaluation of human grB as a potential adjuvant therapeutic agent, especially for treating immunosuppressed patients that bear membrane Hsp70-positive tumors.

Design of human granzyme B variants resistant to serpin B9.

Human granzyme B (hGB) is a serine protease involved in immune-mediated apoptosis. Its cytotoxicity makes it potentially applicable in cancer therapy. However, the effectiveness of hGB can be hampered by the cytosolic expression of a natural protein inhibitor, human Serpin B9 (hSB9). Here, we used computational approaches to identify hGB mutations that can affect its binding to hSB9 without significantly decreasing its catalytic efficiency. Alanine-scanning calculations allowed us to identify residues of hGB important for the interaction with hSB9. Some variants were selected, and molecular dynamic simulations on the mutated hGB in complex with hSB9 in aqueous solution were carried out to investigate the effect of these variants on the stability of the complex. The R28K, R201A, and R201K mutants significantly destabilized the interaction of the protein with hSB9. Consistently, all of these variants also retained their activity in the presence of the Serpin B9 inhibitor in subsequent in vitro assays of wild-type and mutated hGB. In particular, the activity of R201K hGB with and without Serpin B9 is very similar to that of the wild-type protein. Hence, R201K hGB emerges as a promising species for antitumoral therapy applications.

Delivery and therapeutic potential of human granzyme B.

Granzyme B (GzmB) is used by cytotoxic lymphocytes as a molecular weapon for the defense against virus-infected and malignantly transformed host cells. It belongs to a family of small serine proteases that are stored in secretory vesicles of killer cells. After secretion of these cytolytic granules during killer cell attack, GzmB is translocated into the cytosol of target cells with the help of the pore-forming protein perforin. GzmB has adopted similar protease specificity as caspase-8, and once delivered, it activates major executioner apoptosis pathways. Since GzmB is very effective in killing human tumor cell lines that are otherwise resistant against many cytotoxic drugs and since GzmB of human origin can be recombinantly expressed, its use as part of a 'magic bullet' in tumor therapy is a very tempting idea. In this review, we emphasize the peculiar characteristics of GzmB that make it suited for use as an effector domain in potential immunoconjugates. We discuss what is known about its uptake into target cells and the trials performed with GzmB-armed immunoconjugates, and we assess the prospects of its potential therapeutic value.